This invention relates generally to apparatuses and constructions used to produce material deposits in response to fluid flow, and more particularly to a beach erosion control system embodying a sub-tidal platform which is adapted to be positioned on- or offshore from a beach to be protected.
Apparatuses for preventing erosion of beaches, the bottoms and/or banks of rivers or streams, and/or for producing material deposits under water, are well-known in the art. For example, U.S. Pat. No. 226,772 to Mueller discloses a rectangular-shaped, jetty-shutter assembly comprising a vertical wall with hinged gates or slats mounted at their upper ends on horizontal axes on a beach side of the wall. The gates open toward the beach in response to incoming waves or current, and close in response to outgoing waves or current, to deposit sediment on the beach side of the wall between the wall and the beach. The assembly is supported in the water by vertically driven piles.
U.S. Pat. No. 604,810 to Waddell discloses a jetty assembly for deepening a flowing channel. The assembly comprises two rows of interconnected vertical piles inclined outwardly from the shore of the channel to the center thereof. Gates, which are hinged at their tops on horizontal axes, are mounted on one row of the piles so that incoming tide or current can flow through the gates, while outgoing tide or current is obstructed from the outward flow. Thus, a rapid outgoing tide or current is produced on the opposite side of the channel to deepen the channel.
U.S. Pat. No. 1,574,153 to Kellner discloses a jetty of A-frame-type triangular construction for preventing river bank erosion and silt accumulation. Each side and bottom of the triangular jetty includes a plurality of longitudinally extending cables which extend between and from opposite ends thereof. In use, an inner end of one jetty section is located at a 45 degree angle to the river bank and anchored to the bank by the extending cable portions at that end. Additional jetty sections may be interconnected by the extending cable portions at their adjacent ends. In operation, the cable portions defining the sides and bottom of the jetty permit water flow through the jetty sections with deposition of silt occurring on the downstream side of the sections.
U.S. Pat. No. 2,655,790 to Daley discloses a vertical permeable barrier wall formed in sections and mounted on a horizontal platform. The wall includes a series of flexible vanes fixed at their lower ends on horizontal axes and free to flex in either direction in response to wave or current flow, so that water flows through the wall in both directions upwardly to reduce the water's velocity, causing it to drop sediment at the base of the wall on both sides thereof.
U.S. Pat. No. 3,011,316 to Wilson discloses a breakwater having a pair of spaced-apart fences each with a plurality vanes hingedly connected between posts so that they extend along horizontal axes. The purpose of Wilson's breakwater is to dissipate waves along the shores of bodies of water where the waves have a normal tendency to wash away the beach. The vanes are provided for dissipating waves travelling towards the beach.
U.S. Pat. No. 3,214,916 to Martin, as with the aforementioned Mueller patent, discloses a vertical wall assembly with gates hinged at their upper ends on horizontal axes on a beach side of the wall. The gates open toward the beach in response to incoming waves or current, and close in response to outgoing waves or current, to cause deposition of sediment between the wall and the beach. The wall is mounted on embedded posts and each gate carries a pivoted locking bar which embeds in accumulated deposits as they build up adjacent the bottom of the gate, thereby preventing the gate from thereafter opening in response to incoming waves or current and washing away the accumulated deposits.
U.S. Pat. No. 3,966,172 to Garrett discloses a movable fence which is used in protecting areas against wind-blown snow, sand, or the like. As shown in Garret, the fence is triangularly-shaped, and has a plurality of pliant, deformable or resilient strips mounted upon a plurality of A-frame members.
U.S. Pat. No. 4,367,978 to Schaaf et al. discloses a string of prism-shaped modules of triangular cross section and essentially solid construction. Each module has an upper converging passage extending through it from the ocean side to the beach side, so that waves or current flowing through the passage are dissipated in energy. An intermediate passage converges in the same manner and may have a planar flexible gate (valve member) mounted across its beach side opening so that the gate permits incoming wave or current flow through the passage, but blocks outgoing wave or current flow, so that sediment is deposited at the base of the module. In addition, a third lowermost passage is provided with an open bottom to facilitate self-implementation of the module on the ocean floor.
U.S. Pat. No. 4,647,249 to Grooms further discloses an inverted T-shaped member which has a horizontal base and a vertical wall with one-way flexibility. The vertical wall flexes in response to an incoming wave and then returns to a vertical position to impede outward water flow so that sediment settles out on the beach side of the wall.
A disadvantage germane to each of the foregoing systems is that they are expensive to build and are oftentimes subject to failing after a period of time due to the stress of the flow of water therethrough. Also, they tend to starve sand from their downward drive thereby negatively impacting the environmental sanctity of the marine life between the systems and the beaches which they protect.
In general, the present invention is directed to a sub-tidal platform adapted to be placed under water in front of a beach. The platform comprises a support structure having at least two upwardly extending, spaced-apart side walls extending along vertical planes. Each side wall has a bottom adapted to rest on a generally horizontal surface, and a sloping, upwardly extending edge which is at an acute angle with respect to the bottom. A plurality of interconnecting members extend between the side walls for maintaining them in an upright position. The interconnecting members are positioned adjacent to the sloping edge of the side walls. A plurality of gates are pivotally connected to the interconnecting members of the support structure for controlling fluid flow through the space between the side walls. The gates open in response to incoming fluid flow through the gates, and close in response to outgoing fluid flow in the opposite direction. The gates, when in their closed position, combine to form a sloping wall which substantially blocks the flow of fluid through the space between the side walls, and deposits fluid-carried material in the space formed by the side walls and sloped wall.
Accordingly, among the several objects of the present invention are the provision of a sub-tidal platform which is capable of preventing the erosion of a beach in front of which it is placed by causing the natural, slow build-up of material between the sub-tidal platform and the beach; the provision of such a sub-tidal platform which is fabricated from light-weight materials so as to make its implementation easy; the provision of such a sub-tidal platform which is further fabricated from non-corroding materials which extend the life thereof; the provision of such a sub-tidal platform which, over an extended period of time, actually increases the amount of deposit material forming the beach; the provision of such a sub-tidal platform which does not immediately (and negatively) impact the ecology of the beach thereby harming marine life; the provision of such a sub-tidal platform which can easily be removed if necessary; and the provision of such a sub-tidal platform which is relatively simple in construction, cost-efficient to manufacture, and easy to assemble.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.